1. Field of the Invention
The present invention generally relates to asset locator systems, and more specifically to a method and apparatus for identifying the location of an asset.
2. Related Art
An asset, as used in the present application, generally refers to a property which can be moved from one location to another. For example, in the airline industry, passenger bags (assets) are transported across multiple locations (e.g., from check-in place to temporary storage place, to a sequence of flights, and then to check-out place in the destination location).
There is a general need to identify the present location of an asset. In the airline example of above, it is desirable to know in which airport/storage place, etc., a specific baggage is present. The information may then be used to track the location of the asset, if such a need arises, as is well known in the relevant arts.
A prior approach may attach a badge (“asset badge”) to an asset sought to be tracked/located. The badge may transmit a unique identifier periodically, and a reader may be designed to receive/decipher the identifiers. The area covering the location of such badges generally forms the zone of a reader. The reader may forward the identifiers to a central data processing system, using which a user may determine that an asset of interest is within a zone of operation of a corresponding reader.
One problem with the above approach is that the specific position of the asset within that zone may not be identified even approximately. It may be desirable to identify the specific location of an asset within a zone of a reader.example, assuming that an explosion (due to a bomb) is determined to have occurred in a specific location, it may be desirable to know the specific assets that were present around/at that location (for investigation purposes). Unfortunately, it may not be possible to determine the specific location of assets within a zone of the reader.
International application number WO 01/06401 A1 published (hereafter “PCT Application”) under Patent Cooperation Treaty (PCT) entitled, “Method and Apparatus for Mobile Tag Reading” naming Jay Werb as inventor teaches various approaches to determine the specific location of the badges/assets. The approaches there, among other techniques, appear to rely on approaches such as Global Positioning System (GPS) in individual badges (see for example, line 30 page 6 through line 3 page 7 of the PCT Application) or travel time-of-flight of signals between a tag and tag reader (see, for examples, lines 17–25 of Page 9 of the PCT Application).
Unfortunately, implementation of GPS support in individual tags may lead to unacceptably high cost solutions. On the other hand, approaches based on time of flight of signals may not be suitable in situations when assets are closely located since such techniques are generally based on measuring a round-trip time of a signal sent by a reader and reflected by the specific asset. In particular, the reader may not be able to identify which specific one of the tags has reflected the signal, thereby posing challenges in determining the specific location of an asset of interest. In addition, since all badges need to have support for cooperatively reflecting the signals sent by a reader, the total cost of such implementation may also be unacceptably high.
What is therefore needed is a method and apparatus enabling identifying the location of an asset.